The problem with someone like the Count (or, really, most narrators who have done a lot of games) is that he has a very specific style that would be difficult for a co-narrator to replicate. This is especially true for an established series, such as Careless.
Even if one person writes narrations and the other resolves night actions, there can be some issues. I know some of my narrations didn't work at all with what Ramsus had in mind for Center. I know I've seen other series where one person's visualization of the fluff didn't fit with someone else's.